1. Field of Invention
This invention relates to a roll to be processed (hereinafter referred to “roll”) before forming a cell and a grinding method for the roll in which a thickened copper sulfate plating with a uniform thickness having no nibs or pits can be applied to a roll for a gravure printing, a middle finish grinding and a mirror finish grinding not depending on a grinder stone grinding can be carried out within a short period of time and a high quality roll can be provided.
2. Description of Related Art
Two types of printing plate manufacturing method of a roll for a gravure printing will be described as follows.
(1) A laser printing plate manufacturing step for a direct printing plate type roll performs steps for performing a middle finish grinding, a final finish grinding and a mirror surface finish grinding with a grinder stone after performing an ultra precision cylinder machining through a roll loading and lathe, or performing a cell-image cutting and grinding to cut a specified thickness after performing a cylinder grinding to correct it into a true circle by peeling chromium with hydrochloric acid—degreasing—nickel plating—middle finish grinding, final finish grinding and a mirror surface finish grinding by plating with copper sulfate. Then, the subsequent steps are spraying and forming a photo—sensitive film—printing of image with a laser exposure device—development with alkali—forming of a cell with engraving—peeling of resist with strong alkali—chromium plating—grinding with a sand paper—unloading.
(2) A laser printed plate making step for a ballade plating type roll performs steps of loading of roll with used ballade copper plating being removed—degreasing—slight contacting surface treatment coated with photographic waste liquid—copper sulfate plating—middle finish grinding, final finish grinding and mirror surface finish grinding with a grinding stone. Then, subsequent steps are spraying and forming of a photo—sensitive film—printing of image with a laser exposure device—alkali development—forming of a cell with etching—peeling of resist with strong alkali—chromium plating—grinding with a sand paper—unloading.
In addition to the aforesaid steps, there is provided an engraving printed plate made by either an electronic engraving machine or a laser engraving machine and the like.
As the prior art documents related to the gravure printed plate making technology, there are Japanese Patent Application Nos. Hei 10-193551, 10-193552; Japanese Patent Laid-Open Nos. 2000-062342, 2000-062343, 2000-062344, 2001-179923, 2001-179924, 2001-187440, 2001-187441, 2001-191475, 2001-191476, 2001-260304, 2002-127369, 2002-187249, 2002-187250, 2002-200728, 2002-200729, 2002-307640 and 2002-307641 and the like.
In the prior art copper sulfate plating method and device for a process roll for a graver printing, it is well known that an anode including phosphorized copper is used as an anode for electrically plating copper, wherein as one of the anodes including phosphorized copper for this electrical plating, it is known to provide an anode including phosphorized copper having phosphor of 350 to 700 ppm, oxygen of 2 to 5 ppm; and the balance is composition including copper and unavoidable impurities.
The prior art copper sulfate plating method and device for a roll for a gravure printing were set such that a cassette type roll chuck rotary transferring unit was mounted on a main body frame of a plating device, the roll for a gravure printing chucked at its both ends by the cassette type roll chuck rotary transferring unit was connected to a cathode, immersed in plating liquid stored in a plating tank, rotated in it phosphorized copper, balls acting as plating metal immersed in the plating liquid were applied as an anode and a plating current was flowed between the anode and the roll. Then, the phosphorized copper balls including oxygen of 2 to 5 ppm and Phosphor of 350 to 700 ppm are fed into and supplemented to the anode cage of the plating tank to perform plating at a high current density of 10 to 15 A/dm2.
The phosphorized copper balls contain unavoidable impurities and black anode sludge adhere to the surfaces of the plating metallic copper balls. Then, the anode sludge were removed away from the plating metallic copper balls through agitation of liquid and dissolution of the plating metallic copper balls, the sludge floated in the plating liquid, adhered to the roll to become either some nibs (minute protrusions) or pits (pin-holes).
In addition, it was necessary to perform a maintenance work for discharging the plating liquid regularly, diluting the liquid to attain plating liquid having a suitable copper ion concentration so as to eliminate some disadvantages that too much amount of dissolution of the plating metallic copper balls and too high copper ion concentration in the plating liquid prevent an appropriate copper sulfate plating from being carried out.
Further, also in the case of performing an electrical copper plating method for a semiconductor wafer, there employs a method in which the phosphorized copper balls are applied as anode and a plating current is flowed.    [Patent Document 1] Gazette of Japanese Patent Laid-Open No. Hei 5-214586    [Patent Document 2] Gazette of Japanese Patent Laid-Open No. Hei 8-67932    [Patent Document 3] Gazette of Japanese Patent Laid-Open No. Hei 11-061488    [Patent Document 4] Gazette of Japanese Patent Laid-Open No. 2003-171797    [Patent Document 5] Gazette of Japanese Patent Laid-Open No. 2002-275698
In the prior art copper sulfate plating method and device for a process roll for use in a gravure printing, a plating method and a device employing non-soluble anode are not employed at all.
As the copper sulfate plating method using a non-soluble anode other than the method for dissolving the phosphorized copper balls, there are present some technical documents as follows.    [Patent Document 6] Gazette of Japanese Patent Laid-Open No. 2003-166100            [Copper power used in a copper plating method and a method for using copper powder]            [Patent Document 7] Gazette of Japanese Patent Laid-Open No. 2002-068743            [Method for manufacturing easy-dissolving copper oxide; easy-dissolving copper oxide, copper plating material; and copper plating method]            [Patent Document 8] Gazette of Japanese Patent Disclosure No. 2002-515549            [Electrical copper plating method for substrate]            [Patent Document 9] Gazette of Japanese Patent Disclosure No. Hei 08-501827            [Copper electrolytic plating method and device]        
As apparent from the aforesaid printed plate manufacturing steps, there are present several processing steps performed by a grinding-stone type grinder, wherein it takes time more than 30 minutes for a grinding before performing the copper sulfate plating and another grinding after performing the copper sulfate plating. In addition, as the grinding-stone type grinder device, it is necessary to prepare four types of grinding stones, i.e. a rough finishing grinder stone for a cell-cutting, a middle finish grinder stone, a final finish grinder stone and a mirror surface finish grinder stone required up to a mirror surface state. Further, it is necessary to have a general characteristic capable of accommodating for a roll size from 100 mmφ×1,000 mm to 300 mmφ×2000 mm. It is necessary to install an automatic changer mechanism for a grinder stone and two-head grinding or four-head grinding to perform a concurrent grinding from both sides to shorten the required time. Due to this fact, the grinding stone type grinder device is a quite expensive facility. Further, since the grinding stone type grinder device is a wet-type device, this device is not friendly with moisture and cannot be installed in the same room for a photosensitive film coating device or laser exposure device. In turn, this is not constructed such that the roll while being chucked at the cassette type roll chuck rotary transferring unit transferred by a stacker crane installed at the plating line can be ground.
In the case of the prior art method and device for grinding a roll for a gravure printing operation, the electrolytic grinding particle grinding method and device therefore are not employed at all.
As the electrolytic grinder particle grinding method and apparatus therefore, following technical documents are present.    [Patent Document 10] Gazette of Japanese Patent Laid-Open No. Hei 10-156627            [Electrolysis mirror surface finish grinding method for tungsten]            [Patent Document 11] Gazette of Japanese Patent Laid-Open No. Hei 10-086020            [Electrolysis machining method and device for dynamic pressure groove in dynamic pressure bearing]            [Patent Document 12] Gazette of Japanese Patent Laid-Open No. Hei 09-192933            [Minute amount electrolytic machining method and device]            [Patent Document 13] Gazette of Japanese Patent Laid-Open No. Hei 09-192932            [Electrolysis minute groove machining method and device]            [Patent Document 14] Gazette of Japanese Patent Laid-Open No. Hei 07-241728            [Electrolysis grinder particle grinding method for stainless steel]            [Patent Document 15] Gazette of Japanese Patent Laid-Open No. Hei 07-185938            [High-speed electrolytic rough finishing method and device therefore]            [Patent Document 16] Gazette of Japanese Patent Laid-Open No. 06-023663            [Ultra-smoothing non-contact grinding method and device therefor]        
In accordance with the aforesaid prior art copper plating method in which the phosphorized copper balls are applied as anode, non-avoidable impurities are accumulated in the plating liquid, and the non-avoidable impurities adhere to the surface of the process roll to become a cause of forming small particles or pits. Employing the copper plating method with the phosphorized copper balls of high purity being applied as an anode may lead to an increased cost of plating work and so this cannot be employed.
In addition, in accordance with the copper plating method in which the prior art phosphorized copper balls are applied as an anode, a long distance between the anode and the roll caused a plating current to be concentrated at both ends of the roll and further a plating thickness was made high near both ends of the roll. Due to this fact, points near both ends were substantially ground when a grinding for a cylinder member was carried out with a grinder stone. The grinder stone type cylindrical member grinding device is large in size, expensive in its price, it takes much time for a machining work, so that studying of employing the electrolytic grinding device of small-size, less-expensive and requiring a short machining time showed that the electrolytic grinding device cannot perform a grinding operation so as to cause the non-uniform plating thickness to become uniform, resulting in that applying the electrolytic grinding device required a structure of a plating system capable of making a plating thickness uniform over an entire length of the phosphorized copper balls.